一种新的航天器外露介质充电模型

A new charging model for exposed dielectric of spacecraft

为综合考虑高能电子辐射与周围等离子体对航天器外露介质充电的影响,在航天器内带电模型的基础上,通过添加边界充电电流来考虑等离子体与航天器介质表面的相互作用,并统一参考电位为等离子体零电位,建立了航天器外露介质充电模型,给出了新模型的一维稳态解法,并与表面充电模型和深层充电模型进行了对比分析.结果表明:新建模型能够综合考虑表面入射电流、深层沉积电流和传导电流对充电的耦合作用过程,实现外露介质表面和深层耦合充电计算,有利于全面评估航天器外露介质的充电问题.

In order to consider comprehensively the effects of high-energy electron radiation and space plasma on the exposed dielectrics outside a spacecraft, in this paper, a model named surface and internal coupling charging model for the exposed dielectric of spacecraft is proposed, and its numerical solution is obtained. It is based on the deep dielectric charging model, with considering the interaction between the exposed dielectric surface and the ambient plasma by adding an incident charging current into the boundary in the proposed model, and the potential of infinite plasma is regarded as the referential potential（zero potential）. The determinate solution of the model is analyzed and a numerical solution in one-dimensional case is provided by using an iterative algorithm to overcome the coupling between electric field and conductivity. The solution includes the potential of spacecraft body, the distribution of dielectric potential,and the electric field. Moreover, the new model is compared with surface charging model and internal charging model.The results show that the new model has an advatage of depicting the electric field exactly with respect to the surface charging model; if the internal deposition current is equal to zero, the new model degenerates into the one depicting the surface charging. It considers the effect of surface potential on charging results compared with the internal charging model. The three kinds of currents, namely the surface incident current, the internal deposition current and the leakage current, are considered comprehensively in the new model. Among them, the leakage current is the most complicated,which is determined by the potential and the dielectric conductivity affected by the electric field, radiation dose rate,and temperature. Using this new model, the surface and internal coupling charging simulation of the exposed dielectric can be performed. Therefore, the new model can provide a more comprehensive assessment for the charging of exposed dielectric of spacecraft.